http://mongoc.org/libmongoc/current/installing.html appears to have instructions for two use cases:

• Installing a release of libmongoc when another program wants to use libmongoc
• Building libmongoc from source

It appears to not address the use case of someone installing libmongoc to develop an application with it, which could perhaps be the most common use case, and in which situation libmongoc-dev/libbson-dev packages must also be installed.

SO inquiry: https://stackoverflow.com/questions/62289167/compiling-c-program-with-libmongoc-1-0/